Selectively positioned cam means for operating pivoted chaser carriers



Nov. 13, 1956 'R HOTTIAUX 2,769,992

SELECTIVELY P OSITIONED CAM MEANS FOR OPERATING PIVOTED CHASER CARRIERS Filed July 11, 1952 5 Sheets-Sheet l INVENTOR ROMND H0 TT/AUX i ATTORNEYS Nov. 13, 1956 HOTTIAUX 2,769,992

R. SELECTIVELY POSITIONED C-AM MEANS OPERATING PIVOTED CHASER CARRIE Filed July 11, '1952 5 Sheets-Sheet 2 RQLAND HOW/AUX MVM ATTORNEYS Nov. 13, 1956 R HOTTIAUX 2,769,992 v SELECTIVELY P OSITIONED CAM MEANS FOR OPERATING PIVOTED CHASER CARRIERS Filed July 11, 1952 5 Sheets-Sheei 3 "I'll I I ill w INVENTOR ROLAN W 1" ATTORNEYS United States Patent O SELECTIV ELY POSITIONED CAM IVIEANS FOR OPERATING PIVOTED CHASER CARRIERS Roland Hottiaux, Bogny, Braux, France Application July 11, 1952, Serial No. 298,413 Claims priority, application France July 13, 1951 3 Claims. (Cl. -100) The present invention relates to tangent chaser screwing stocks in which the chaser holders are held axially by means of a central flange and driven in rotation each about an axis rigid with the chaser holder through a shoulder rigid with an exterior cage. Said exterior cage is mounted for movement necessary to close and open the chaser holder at each screwing cut, and for rotation with respect to the body of the screwing stock for diametrical adjustment of the chaser holders.

To achieve these two movements, it has so far been necessary to use arrangements which cause a rapid wearing of the shoulder and require frequent change of the exterior cage with which they are rigid.

It is also known, as a matter of fact, that with the screwing stocks now in use, it is very difficult to obtain a correct distribution of the chasers round the work piece. The errors in construction of the screwing stock, however small, add to the errors in thickness of the chasers which are often considerable, so that in order to obtain an accurate screwing, the adjusters must fix the chasers at too low a level, with feeler gauges. This is an unpleasant, lengthy and inaccurate method which must be carried out at every grinding.

This invention has for its purpose to obviate these drawbacks and the improvements which form its object consist, to this end, of:

l. Replacing the paired rings of the screwing stocks now in use by a single crown on which are secured for ready removal flat abutting members, equal in number to the chaser-holders; said abutting members coming into contact with the chaser-holders, so as to cause pivoting thereof at the desired moment, through either one of their fiat surfaces so as to form through the intermediary of the corresponding abutting member, a contact of the chaser-holder with the outer bearer which is no longer a point-contact but a linear contact and therefore have a low unit contact pressure, and, in consequence, reduced wear.

2. Providing said abutting members so that the distances between their axis and each possible contact fiat surface thereof with the corresponding chaser-holder,

instead of being the same, may be different and that the difference may increase by a predetermined value, 1 or 2/100 mm. for instance, from one side to the previous one. Accordingly, by previously rotating each of the abutting members, one or another fiat side thereof is brought into contact with the corresponding chaserholder whereby the concentricity of the chaser will be instantly adjusted, and it is possible to return to the initial position without error.

The above mentioned two improvements can be used singly or in combination.

Further characteristics of the invention will appear from the following description of a particular embodiment given by way of non limitative example, with reference to the attached drawings.

In the drawings:

Fig. 1 is a diagrammatical front view of a screwing 2,769,992 Patented Nov. 13, 1956 stock on which only one abutment and one chaser-holder are shown, with a part broken off showing the shank of another abutment in section along line I-I of Fig. 4.

Fig. 2 is a partial longitudinal sectional view along line II-II of Fig. 3 with, at bottom of the figure a partial view of the crown along II'II' of Fig. 7.

Fig. 3 is a partial sectional view along line III-III of Fig. 2.

Fig. 4 is a side elevation of an part of the present device.

Fig. 5 illustrates diagrammatically how a chaser-holder is contacted by an abutment.

Fig. 6 is an isometric perspective view of a key also forming a part of the present device.

Fig. 7 is a partial rear view of the crown.

Fig. 8 is an enlarged front view of the head of an abutment.

Around the body 1 of the screwing stock, which can be rotatably driven by the shaft 2, there is slidably mounted a crown 3 having an inner annular groove 4 engaged by the collar 5 of a key 6 freely slidable in a groove 7 of said body 1 (Fig. 2).

An endless screw 8, rotatably supported and retained by a screw 9 in a recess of the crown 3, meshes with a threaded curved section 10 of the key 6. The rotation of the endless screw 8 provides for the angular displacement of the crown 3 about the body 1 by moving said crown 3 about said body 1 within the limits determined by the angles a1 and 042 (Fig. 3). The assembly composed of the crown 3, endless screw 8, and key 6 is movable longitudinally on the body 1 to provide for the opening and closing of the screwing stock.

The crown 3 is provided with a groove 11 whereby upon removing the endless screw 8 the crown 3 can be rotated and moved forwardly whereupon "the collar 5 of the key 6 passes through the groove 11 (Figs. 2 and 7) freeing said crown.

The four chaser-holders, only one of which is shown at 12 (Fig. 1) are each pivotally supported by a spindle 13 inserted in an opening in body 1. Each chaser-holder has a shoulder 14 extending on a slant across the bottom face thereof for being contacted by an abutment 15 (Figs. 1, 2, 4 and 5) which is pivotable about its shank 16 extending into an opening in the crown 3. A screw 17, the head 18 of which fits into a circular groove 19 (Figs. 1 and 4) of said shank 16 extends within crown 3 and prevents the longitudinal movement of each shank 16.

During the forward movement of assembly comprising the crown 3, screw 8 and key 6 in the direction of the arrow 1 of Figs. 2 and 5, each one of the four abutments 15 bears through its chamfered end 20 onto the bevelled rim 21 of the shoulder 14 of the corresponding chaser-holder 12 (Fig. 5) causing the latter to pivot on its spindle 13 and bring its chaser into contact with the workpiece 23 (Fig. 1).

During the opposite movement of said assembly, each abutment 15 will free its corresponding chaser-holder 12 which pivots in the direction of the arrow 1" of Fig. 1 releasing its chaser 22 from the workpiece 23.

As it has been shown before, under the action of the endless screw 8, the crown 3 rotates around the body 1 by an angle the value which can amount to 0:1 or a2. Fig. 1 shows that to each of these angular oscillation limits of crown 3 there is a corresponding position 1616" of each of said abutments 15. Such an angular adjustment of the crown 3 with its abutments 15 corresponds to the diametrical adjustment of the chasers 22.

The four sides a, b, c, d of each one of the four abut abutment forming a By imparting a rotation motion to one of the four abutments 15, said four sides a, b, c, and d coming into contact one or another with the shoulder 14 of the corresponding chaserholder 12, will act differentially on said shoulder by: e, 2e, 3s. The radial position of the corresponding chaser 22 may therefore be caused to vary within the limits of:

e+2e+3e 6 being a predetermined value of 1 or 2/ 100 mm. for instance. And the spacing between two opposite chaserholders may vary from to 66 by multiples of e.

As shown on Figs. 1 and 2; 24 refers to a central flange extending laterally from the end of sleeve 25, holding axially the chaser-holder 12 by insertion in a side slot in the chaser-holder.

What I claim is:

l. A screwing stock head comprising an annular body having a central opening for supporting the workpiece therethrough, a plurality of chaser-holders pivotally mounted on said body around said opening, a crown positioned around said body and rotatably supported thereon for moving circumferentially of said body, said body having a longitudinal slot provided in the periphery thereof, said crown having an annular laterally extending slot provided in the inner face thereof, a key slidably and detachably mounted in said body slot and also in said crown slot providing longitudinal and lateral connection therebetween, said key having a threaded lateral section, said crown having a lateral bore, a screw mounted in said crown bore and being in threaded engagement with said key threaded section for rotating said crown, a plurality of abutments each mounted on said crown and positioned for engaging and pivoting one of said chaser-holders towards said workpiece upon axial movement in one direction of said crown and means tending to move said chaser holders from said work piece when said abutments are moved from said chaser holders.

2. A screwing stock head comprising an annular body having a central opening for supporting the workpiece therethrough, a plurality of chaser-holders pivotally mounted on one side of said body around said opening, a crown slidably mounted around the periphery of said body, means for guiding said crown during movement thereof longitudinally of said body, means for rotating said crown around the periphery of said body, a plurality of abutments each mounted on the side of said crown corresponding to said chaser-holders and capable of axial rotation, each of said abutments having a chamfered end portion with the faces of said charnfer being positioned at varying distances from the axis of said abutment, said chaser-holders each having a shoulder provided on the bottom face thereof for being contacted by one of said abutments upon axial movement of said crown in one direction pivoting the chaser-holder towards the workpiece, means tending to move said chaser-holders from said workpiece and each chaser-holder shoulder having a chamfered edge for being initially contacted by the chamferedt portion of one of said abutments for adjusting the position of the connected chaser diametrically of said body a distance depending on the chamfered face of the abutment selected.

3. A screwing stock head comprising an annular body having a central opening for supporting the workpiece therethrough, a plurality ofv chaser-holders pivotally mounted on one side of said body around said opening, a ring crown having said body rotatably mounted therein, means for rotating said crown. around said body, a plurality of abutments carried by said crown on a side thereof corresponding to said side of said body, means for rotating said abutments about their axis, each of said abutments having sides thereof positioned at varying dis tances from the axis of said. abutment, said chaser-holders each having a substantially straight side thereof extending across said crown face for being contacted by one of said abutment sides. and pivoted thereby towards the workpiece and means tending to pivot said chaserholders towards said abutments.

References Cited in the file of this patent UNITED STATES PATENTS Cashman Apr. '29, 1924 

